AN IDEA may be dangerous either to its conceiver or to others, including its proponents. Four hundred years ago, heliocentricity was acutely dangerous to Galileo, whom it led before the Holy Inquisition. Two and a half centuries later, Darwin's notions on natural selection and the evolution of species jeopardised the certainties and imperilled the livelihoods of many professional Christians. To this day, the idea that God does not exist is dangerous enough to get atheists murdered in America.

The editor of this anthology of dangerous ideas, John Brockman, is, among other things, the publisher of Edge, the "Third Culture" website (www.edge.org). He has already published What We Believe but Cannot Prove, to which this volume is a companion. Each year, Brockman asks a question of his contributors. Last year's was: "What is your dangerous idea?" He meant not necessarily a new idea, or even one which they had originated, but one which is dangerous "not because it is assumed to be false but because it might be true". This volume, with an introduction by Steven Pinker and an afterword by Richard Dawkins, publishes the responses given in 2006 by 108 of "Today's Leading Thinkers on the Unthinkable".

...There is much in many of these brief essays to astonish, to be appalled at, to mull over or to wish for. Some of them suffer from galloping emailographism, that mannerism of the hasty respondent whose elliptical prose can make even the most pregnant idea indigestible. But most of them, from the three-sentence reminder by Nicholas Humphrey of Bertrand Russell's dangerous idea ("That it is undesirable to believe in a proposition when there is no ground whatever for supposing it true") to the five pages of V.S. Ramachandran on Francis Crick's "Astonishing Hypothesis" (that what we think of as our self is merely the activity of 100 billion bits of jelly, the neurons which constitute the brain), are vitally engaging to anyone with an ounce of interest in matters such as being or whatever

...Mind you, there is one glimpse of the future which rings grotesque enough to be plausible, Gerald Holton's "Projection of the Longevity Curve", in which we see a future matriarch, 200 years old, on her death bed, surrounded by her children aged about 180, her grandchildren of about 150, her great-grandchildren of about 120, their offspring aged in their 90s, and so on for several more generations. A touching picture, as the author says, "But what are the costs involved?"

'What are you optimistic about?" editor John Brockman asked some of the world's leading scientists on his Web site, www.edge.org.

As I've yet to complete my unified theory of the universe, he did not include me in his survey. If he had, I'd have answered: Just about everything.

As I reported in last week's column, Brockman's respondents were forward-looking, describing cutting-edge research that will help combat global warming and other looming problems. My optimism is anchored in the past.

By almost any measure -- greater wealth, better health, diminishing levels of violence -- the world is good and getting better. My only regret is that I am alive today because tomorrow will be even brighter.

Where to start with the good news? How about with the Big Kahuna: During the 20th century, life spans for the average American rose from 44 years to 77 as we tamed age-old scourges such as smallpox, malaria, polio and plague.

In particular, I am optimistic about humanity's prospects for starting exemplary new collaboratively developed knowledge resources. When we hit upon the correct models for collaborative knowledge-collection online, there will be a jaw-dropping, unprecedented, paradigm-shifting explosion in the availability of high-quality free knowledge.

A few years ago, I wrote a short book entitled 'Our Final Century'. I guessed that, taking all risks into account, there was only a 50 per cent chance that civilisation would get through to 2100 without a disastrous setback. This seemed to me a far from cheerful conclusion. However, I was surprised by the way my colleagues reacted to the book: many thought a catastrophe was even more likely than I did, and regarded me as an optimist. I stand by this optimism....

I am optimistic about human relationships - in particular, about friendship. Perhaps you have heard gloomy predictions about friendship: it's dying out, people no longer have friends they can confide in, loneliness is on the rise....

The full-length versions of these pieces (and many more) can be found at www.edge.org, a website founded by John Brockman.'What Is Your Dangerous Idea?', by John Brockman (Editor), is published by Simon & Schuster, £12.99; 'What We Believe But Cannot Prove', by John Brockman (Editor), is published by Pocket Books, £7.99

...You might think scientists would be the optimistic exception here. Science, after all, furnishes the model for progress, based as it is on the gradual and irreversible growth of knowledge. At the end of last year, Edge.org, an influential scientific salon, posed the questions "What are you optimistic about? Why?" to a wide range of thinkers. Some 160 responses have now been posted at the Web site. As you might expect, there is a certain amount of agenda-battling, and more than a whiff of optimism bias. A mathematician is optimistic that we will finally get mathematics education right, a psychiatrist is optimistic that we will find more effective drugs to block pessimism (although he is pessimistic that we will use the, wisely). But when the scientific thinkers look beyond their own specializations to the big picture, they continue to find cause for cheer - foreseeing an end to war, for example, or the simultaneous solution of our global warming and energy problems. The most general grounds for optimism offered by these thinkers, though, is that big-picture pessimism so often proves to be unfounded. The perennial belief that our best days are behind us is, it seems, perennially wrong.

Such reflections may or may not ease our tendency toward global pessimism. But what about our contrary tendency to be optimistic - indeed, excessively so - in our local outlook? Is that something we should, in the interests of cold reason, try to disabuse ourselves of? Optimism bias no doubt causes a good deal of mischief, leading us to underestimate the time and trouble of the projects we undertake. But the mere fact that it is so widespread in our species suggests it might have some adaptive value. perhaps if we calculated our odds in a more cleareyed way, we wouldn't be able to get out of bed in the morning. ...

What Is Your Dangerous Idea?, edited by John Brockman (Simon & Schuster, £12.99)

The results of the 2005 Question at edge.org, posed by Steven Pinker, are in. Apart from an exasperating section about "memes" (are they still fashionable?) and a few Eeyorish dullards, it's a titillating compilation. Physicist Freeman Dyson predicts that home biotech kits will become common; others posit that democracy may be a blip and "on its way out", that "heroism" is just as banal as evil, and that it will be proven that free will does not exist. There are also far-out but thought-provoking notions: that, given the decadent temptations of virtual reality, the only civilisations of any species that survive to colonise the galaxy will be puritan fundamentalists; or that the internet may already be aware of itself. I particularly enjoyed cognitive scientist Donald D Hoffman's gnomic pronouncement that "a spoon is like a headache", and mathematician Rudy Rucker's robust defence of panpsychism, the idea that "every object has a mind. Stars, hills, chairs, rocks, scraps of paper, flakes of skin, molecules". Careful what you do with this newspaper after you've read it.

Welcome in the New Year with the Guardian's science team as they ask what we can be optimistic about in 2007. Thinkers such as the Darwinian philosopher Dan Dennett and psychologist Steven Pinker are looking forward respectively to the end of religion and war in 2007—or at least, the beginning of the end. Hear more predictions from web guru and editor of Edge magazine John Brockman.

The affair called to mind a certain meme that I had mentally buried (in the Digg user's sense) but am now forced to revisit with a more open mind. In the November Discover, tech ponderer Jaron Lanier expressed his dismay over the increasing prevalence of "wisdom of crowds" approaches to aggregating information online. See especially Wikipedia and Digg as instances of this phenomenon, also called Web 2.0. Lanier must consider that term itself a masterpiece of framing; he sees a growing glorification of online wisdom-aggregation, and has dubbed the trend Digital Maoism. ...

Anyway, this sort of asymmetrical flamewar doesn't seem to be Lanier's main objection to Digital Maoism. A while back at the Edge.org, on which big brains convene to butt heads, Lanier's argument was abbreviated thusly:

The problem is [not Wikipedia itself but] in the way the Wikipedia has come to be regarded and used; how it's been elevated to such importance so quickly. And that is part of the larger pattern of the appeal of a new online collectivism that is nothing less than a resurgence of the idea that the collective is all-wise, that it is desirable to have influence concentrated in a bottleneck that can channel the collective with the most verity and force. This is different from representative democracy, or meritocracy.

...Into my season of gloom, a ray of hope arrived the other day via the Internet, benefit of the Web site called Edge.

As I understand it, Edge is an electronic gathering place for scientists, artists and other creative thinkers. Most of them are out traveling on the far reaches of the high-tech superhighway, sending us their postcards from a few years in the future. ...

Chris Anderson, who is the curator for an intellectual gathering called the TED Conference, makes a similar point. He says that the number of armed conflicts has declined worldwide by 40 percent in the past decade.

If the world seems ever more threatening, it is because we are wired to respond more strongly to threats than we are to good news. Besides, good news such as scientific discovery and economic progress is largely under-reported in the media, while disaster and doom are hugely over-reported.

I was cheered by the optimism of a science writer who thinks that we will soon have a technological breakthrough that will make solar energy dirt cheap long before the big energy crunch arrives. He's not sure which of the many bright ideas he has written about will be the one that works, but he has faith in the scientists who are pushing at the boundaries of the technology. ...

The Edge contributors fanned the flame of optimism in me in the season of darkness.

EVERY YEAR SINCE 1996, the online salon Edge has e-mailed a question to scientists and thinkers about the state of the world. This year's question was: "What are you optimistic about?" Below are excerpts of some of the responses. For full responses (and those of other contributors), go to http://www.edge.org .

OPTIMISM IS almost a dirty word these days. Global warming, the situation in Iraq, poverty, AIDS and other seemingly unsolvable problems can make us feel a bit blue. To our rescue comes John Brockman, from the Edge World Question Center. This year's poser: What are you optimistic about? "While conventional wisdom tells us that things are bad and getting worse, scientists and the science-minded among us see good news in the coming years." This is the 10th anniversary of the Annual Question; 160 thinkers weighed in.

THE new year is a time for reflection and re-evaluation. It is a process that can leave one feeling up and optimistic or distinctly depressed. If you need some reasons to be cheerful, read on.

The impact of science and technology has been overwhelmingly positive. In a few hundred years life has been transformed from short and brutish to long and civilised. Improvements are spreading (admittedly too slowly) around the planet. Of course, some discoveries and inventions have led to serious problems, but science and technology often provide ways to monitor and alleviate those problems, from ozone destruction to overproduction of greenhouse gases.

And further benefits are coming. To take one example from this issue, researchers have made a drug to treat hepatitis C that should be affordable even in poor countries . Then there is the extent to which cellphones are improving life for the world's poor, the numerous ideas for harnessing energy from sunlight, that human intelligence can be increased and that a revolution in personal genomics is in the wings. These ideas come from www.edge.org, which asked 160 scientists and intellectuals what they are optimistic about. One way or another the answers should give you a warm glow - either because you agree, or because they make you angry.

If you are still left thinking your glass is half empty, check out the submission by Randolph M. Nesse of the University of Michigan, Ann Arbor. He predicts that we will find a way to block pessimism. The consequences may not be all good, but it's a safe bet that science and technology will come to the rescue.

Edge's future-themed article is making some news. Britain's Guardian has summarized some of its contributors' thoughts. ...

...Among many provocative observations in Edge's wide-ranging survey are those of musician, composer and record producer Brian Eno (David Bowie, U2, Talking Heads). Eno writes: "The currency of conservatism...has been that markets are smarter than governments," a notion that "has reinforced the conservative resistance to anything resembling binding international agreements."

However, Eno notes, the "suggestion that global warming represents a failure of the market is therefore important." Will a phenomenon like the warming trend force governments around the world to finally work together in earnest? If they do, and if "a single[,] first instance of global governance proves successful," Eno argues, "it will strengthen its appeal as a way of addressing other problems - such as weapons control, energy management, money-laundering, conflict resolution, people-trafficking, slavery, and poverty. It will become increasingly difficult for countries [like the U.S.] to stay outside of future treaties like Kyoto - partly because of international pressure but increasingly because of pressure from their own populations."

In his Edge contribution, Eno really does sound optimistic. He also writes: "Something like real democracy (and a fair amount of interim chaos) could be on the horizon. The Internet is catalyzing knowledge, innovation and social change,...proving that there are other models of social and cultural evolution[,] that you don't need centralized, top-down control to produce intelligent results. The bottom-up lesson of Darwinism, so difficult for previous generations, comes more naturally to the current generation. There is a real revolution in thinking going on at all cultural levels...."

The assigned purpose of the influential Web magazine, Edge, is lofty enough. It’s to seek out the most complex and sophisticated minds, put them in a room together, and have them ask each other the questions they are asking themselves.

Recently, Edge asked a group of world class scientists and thinkers its 10th Anniversary Question: “What are you optimistic about and why? Among the respondents were leading American philosopher Daniel C Dennett and evolutionary biologist Richard Dawkins— both pretty rabid proponents of atheism.

Dennett was of the opinion that within 25 years religion will command little of the awe it instils in people today and their fascination for it will disappear. He said the spread of information through the Internet, television and cell phones will generally and irresistibly undermine the mindsets requisite for religious fervour.

Dawkins maintained that once scientists discover the so-called “theory of everything” it would be the end of the road as far as faith was concerned. “This final scientific enlightenment,” he said, “will deal an overdue death blow to religion and other juvenile superstitions.”

...Thanks in part to the actions of a few jihadists in September 2001, it is believers who stand accused, not freethinkers. Among the prominent atheists who now sermonize to the believers in their midst are Dr. Dawkins, Daniel C. Dennett ("Breaking the Spell") and Sam Harris ("The End of Faith" and, more recently, "Letter to a Christian Nation"). There are others, too, like Steven Weinberg, the Nobel Prize-winning physicist, Brooke Allen (whose "Moral Minority" was a celebration of the skeptical Founders) and a host of commentators appalled by the Intelligent Design movement. The transcript of a recent symposium on the perils of religious thought can be found at a science Web site called edge.org.

There are many themes to the atheist lament. A common worry is the political and social effect of religious belief. To a lot of atheists, the fate of civilization and of mankind depends on their ability to cool -- or better, simply to ban -- the fevered fancies of the God-intoxicated among us.

Naturally, the atheists focus their peevishness not on Muslim extremists (who advertise their hatred and violent intentions) but on the old-time Christian religion. ("Wisdom dwells with prudence," the Good Book teaches.) They can always haul out the abortion-clinic bomber if they need a boogeyman; and they can always argue as if all faiths are interchangeable: Persuade American Christians to give up their infantile attachment to God and maybe Muslims will too. In any case, they conclude: God is not necessary, God is impossible and God is not permissible if our society -- or even our species -- is to survive. ...

The folks over at Edge.org, a small corner of the interwebs filled with some of the most surprisingly literary smarty-pants science types, asked their Question of 2007: What are you optimistic about?

Not that we were asked, but Seattlest is optimistic that someone will figure out that whole time-travel business, so we can go back and see James Brown in 1964. We did not see him the two times he performed in Seattle since we moved here (2000 at the EMP opening and again in 2003) and each time we neglected to buy tickets, we thought that despite the fact that it would never compare to JB in '64, we'd regret our inaction someday. And so we do.

Video of either Seattle show is nowhere to be found online, so instead we present to you what we will see in person someday, even if it means we have to scrounge up a battered old DeLorean: ...

[I'm Confident About Energy, the Environment, Longevity, and Wealth; I'm Optimistic (But Not Necessarily Confident) Of the Avoidance Of Existential Downsides; And I'm Hopeful (But Not Necessarily Optimistic) About a Repeat Of 9-11 (Or Worse)]

Optimism exists on a continuum in-between confidence and hope. Let me take these in order.

I am confident that the acceleration and expanding purview of information technology will solve the problems with which we are now preoccupied within twenty years.

Ray Kurzweil is inventor and technologist. The shortened contribution appeared on New Years in the Internet magazine Edge (www.edge.org) (http://www.edge.org), on scientists and their Optimism for the coming year.

With the new year comes new resolutions, and new questions, including the new Edge.org question. The science super-hero club house that brought you dangerous ideas in 2006 wants to bring you optimism in 2007.

Each year the Edge, a Web site that aims to bridge the gap between scientists and other thinkers, asks a question of major figures associated with the science world. This year's query: "What are you optimistic about? Why?"

Some respondents, such as biologist and entrepreneur J. Craig Venter, said he was hopeful science's empirical, evidence-based methods would be extended "to all aspects of modern society."

But some scientists clearly were hoping to limit expectations. Robert Trivers, a Rutgers University biologist, says the good news is "there is presently no chance that we could extinguish all of life -- the bacterial 'slimosphere' alone extends some 10 miles into the earth -- and as yet we can only make life truly miserable for the vast majority of people, not extinguish human life entirely."

...Here is the response of Meagan McArdle, not exactly a religious fundamentalist but probably smarter than the 150 scientists and intellectuals put together:Let me see if I can phrase this in a way that Mr Dennett might understand: if smoking made us live forever, it would be very, very popular. Even if it didn't make you live for ever, but could convince enough people that it might, it would be very, very popular. And anyone who thinks that they have the same caliber of evidence for atheism that we do for the carcinogenicity of tobacco needs to have his ego examined for possibly fatal inflammation.

As I make my way through life and try to sort things out, I need the help of both dreamers and thinkers. I just wish they would keep their missions straight, although the intellectuals lately encroach more into the wishful-thinkers' territory than the artists do into the scientists'. At least I never heard Lennon sing, "Imagine quantum physics, it would make Einstein cry . . ."

... Carlo Rovelli, a physicist at the Mediterranean University in Marseilles, France, believes that 'the divide between rational scientific thinking and the rest of our culture is decreasing'. 'In the small world of the academia, the senseless divide between science and the humanities is slowly evaporating. Intellectuals on both sides realize that the complexity of contemporary knowledge cannot be seen unless we look at it all,' he writes.

According to Chris DiBona, Open Source Programs Manager, Google Inc, 'Widely available, constantly renewing, high resolution images of the Earth will end conflict and ecological devastation as we know it.'

Ernst Pöppel, a neuroscientist at Munich University, is optimistic about fighting 'monocausalitis', the tendency to search for one single explanation for a phenomenon or event. 'Biological phenomena can better be understood, if multicausality is accepted as a guiding principle,' he writes.

An eagerly-awaited collider carries Maria Spiropulu's hopes for 2007. Dr Spiropulu is a physicist at CERN. 'Being built under the Jura on the border of Switzerland and France the Large Hadron Collider is a serious reason of optimism for experimental science. It is the first time that the human exploration and technology will offer reproducible 'hand-made' 14 TeV collisions of protons with protons. The physics of such interactions, the analysis of the data from the debris of these collisions [the highest energy such] are to be seen in the coming year,' she writes.

...It doesn’t matter whether you’re making a resolution for the new year or a new day. The point is to change who you are. It’s not always a case of completely transforming yourself: you just want to be recognized as something other than one of David Berreby’s zombies.

An online forum conducted by Edge.org recently asked a slew of scientists and intellectuals what they are optimistic about. Berreby, the author Us and Them: Understanding Your Tribal Mind, said he was hopeful that the idea of a “zombie identity is coming to an end, or at least being put into greater context. I’ll let Berreby explain the notion of a zombie identity himself.

“(It’s) the intuition that people do things because of their membership in a collective identity or affiliation,” he writes. “It's a fundamental confusion that starts with a perhaps statistically valid idea (if you define your terms well, you can speak of ‘American behaviour’ or ‘Muslim behaviour’ or ‘Italian behaviour’)—and then makes the absurd assumption that all Americans or Muslims or Italians are bound to behave as you expect, by virtue of their membership in the category (a category that, often, you created).”

Daniel C. Dennett, a philosopher and cognitive scientist at Tufts University who has written extensively about free will, said that “when we consider whether free will is an illusion or reality, we are looking into an abyss. What seems to confront us is a plunge into nihilism and despair.”...

A vote in favor of free will comes from some physicists, who say it is a prerequisite for inventing theories and planning experiments.

That is especially true when it comes to quantum mechanics, the strange paradoxical theory that ascribes a microscopic randomness to the foundation of reality. Anton Zeilinger, a quantum physicist at the University of Vienna, said recently that quantum randomness was “not a proof, just a hint, telling us we have free will.” ...

If by free will we mean the ability to choose, even a simple laptop computer has some kind of free will, said Seth Lloyd, an expert on quantum computing and professor of mechanical engineering at the Massachusetts Institute of Technology.

Every time you click on an icon, he explained, the computer’s operating system decides how to allocate memory space, based on some deterministic instructions. But, Dr. Lloyd said, “If I ask how long will it take to boot up five minutes from now, the operating system will say ‘I don’t know, wait and see, and I’ll make decisions and let you know.’ ”

Why can’t computers say what they’re going to do? In 1930, the Austrian philosopher Kurt Gödel proved that in any formal system of logic, which includes mathematics and a kind of idealized computer called a Turing machine, there are statements that cannot be proven either true or false. Among them are self-referential statements like the famous paradox stated by the Cretan philosopher Epimenides, who said that all Cretans are liars: if he is telling the truth, then, as a Cretan, he is lying.

One implication is that no system can contain a complete representation of itself, or as Janna Levin, a cosmologist at Barnard College of Columbia University and author of the 2006 novel about Gödel, “A Madman Dreams of Turing Machines,” said: “Gödel says you can’t program intelligence as complex as yourself. But you can let it evolve. A complex machine would still suffer from the illusion of free will.”

Conventional wisdom tells us that things are bad and getting worse. Yet according to Edge — the heady website for world-class scientists and thinkers, and the brainchild of author and entrepreneurial idea man, John Brockman, there's good news ahead. Each year, through their World Question Center, they pose a provocative query to their high-minded community.

Several of us from BoingBoing participated: here'sCory's response ("Copying Is What Bits Are For"), here'sPesco's ("We're Recognizing That the World Is a Wunderkammer"), here's mine (" Truth Prevails. Sometimes, Technology Helps.").

People's fascination for religion and superstition will disappear within a few decades as television and the internet make it easier to get information, and scientists get closer to discovering a final theory of everything, leading thinkers argue today.

The web magazine Edge (www.edge.org) asked more than 150 scientists and intellectuals: "What are you optimistic about?" Answers included hope for an extended human life span, a bright future for autistic children, and an end to violent conflicts around the world.

Philosopher Daniel Denett believes that within 25 years religion will command little of the awe it seems to instil today. The spread of information through the internet and mobile phones will "gently, irresistibly, undermine the mindsets requisite for religious fanaticism and intolerance".

Biologist Richard Dawkins said that physicists would give religion another problem: a theory of everything that would complete Albert Einstein's dream of unifying the fundamental laws of physics. "This final scientific enlightenment will deal an overdue death blow to religion and other juvenile superstitions."

• 'Jeremiahs' list their great hopes for 2007
• More romance, better old age and better death

Scientists often find themselves accused of pessimism. From the gravity of their public warnings about the dangers of climate change or bird flu, they have earned a reputation as Jeremiahs with a bleak view of human nature and humanity’s future.

It is a charge most researchers contest vigorously: science, they say, is a profoundly optimistic pursuit. The idea that the world can be understood by gathering evidence, to the ultimate benefit of its citizens, lies at its heart. It is not just about problems, but about finding the solutions.

The breadth of this optimism is revealed today by the discussion website Edge.org — often likened to an online scientific “salon” — which marks every new year by inviting dozens of the world’s best scientific minds to answer a single question. For 2007, it is: “What are you optimistic about?” The answers show that even in the face of such threats as global warming and religious fundamentalism, scientists remain positive about the future.

The World Question Center at www.edge.org every year asks scientists, doctors, philosophers and educators a question.

The question for 2006 was "What is your dangerous idea?"

Princeton University professor of astrophysics Piet Hut posted this idea:

"In everyday experience, time flows, and we flow with it. In classical physics, time is frozen as part of a frozen spacetime picture. And there is, as yet, no agreed-upon interpretation of time in quantum mechanics.

"What if a future scientific understanding of time would show all previous pictures to be wrong, and demonstrate that past and future and even the present do not exist? That stories woven around our individual personal history and future are all just wrong? Now that would be a dangerous idea."

We hope we've reassured you, dear reader, that those crow's feet do not really exist. They are just an illusion.

Still, here on Earth, we like to celebrate the passage of time. Like we did last night. That's why our head hurts this morning and we don't have much of an appetite.